Telephone system.



J. J. COMER.

TELEPHONE SYSTEM. APPLICATION FILED DEC. 19, 1912. 1,185,879. Patented June 6,1916

Tum:

WITNESS/5'5 Cir , UNITED STATES PATENT OFFICE.

JOHN J'. COMER, 0J3 C HZCAGG, ILLIN 01's, ASSIGNOIR TO AUTOMATIC ENUINCIATOR COM- PANY, OF CHICAGO. ILLILEGIS, A CORPORATION OF ILLINOIS.

'I'ELEPHUNE SYSTEM'.

Application. December 19 To ii/ whom it i m i column lie it known limit I. Join ii. citizen of the l niicd States 0" and resident of (hie (o h mite nois have invenlcd a an own ful lniprm'cmcnt in 'l'eivphonu S1 of \VlilP the icllouing is a speitilicai'ioiu My invention relates to improrei sis in telephone s qsimns,

2m morc particularly to those S-sysiems which arc ei iploycd for ii an mitting ocal or ilifsilllilliflliili HUM-l") in this connection it f und limvl is :nldiir mgr-(ms 1o cuiplcq/ what is known as a dil lcrcntial lransmitlcr-lhat is, a tisliisiilil ter which consists of a pair oi relatively stationary klilflltil fr between which is lo- (filtell a rrlal'iwlv elccthiuie. in using ibis lypc o5. lmmsmiiter, ii. ha herw tol'oic lawn alilliiiliil. if; izroxide :1 circuit arrzmo'e'u i nt wh l) would ransmit over the line the toial combined effect of (be two parts of this diii'creutial transmitter, as the variations of current produced by one half of thc transmitter nould have a tendency to counteracl oi. uck the variations pro- (lured by the othcr hall unless special provisions were {alien to prevent such operations.

The object oi my invention is to provide an improved circuit alignment whereby such il l l'ililfiliil ii'il' ("an be coiplo 2d and in hich the total arcimiulalivc (aiect' obtained, there being: no tenth cy of one part of the iransmillcr to burl; or oppose the other part. li y muliiolying together a plnralitv of those {mnsunlie and ihen no. ncct ng tlicm lo a plurality ol' lino circuits in which are located suitable mpliiicrs, I am, able to employ as many as ten receivers on each line circuit, and Win-re ton of such lino circuits are luhcn from the bus bar it will be seen that I :Xlll able to furnish op-' crating current to one hundred receivers from a single set o1" irunsniitiers.

My invention will be more muddy widen stood by reference to the a cornpanying drawings. in which--- Figuic 1 shows, d

I agramnnirical[y a circuit arrangement as applied to a single line circuit. .l 'ig. .2 shows a siinih r arrange ment, showing, in addition the mann r in which a plurality of these circuits are cou1- bined together. Fig. 3 a diagraminalic View showing more clearly will. manner in Specification of Letters Patent.

Patented June 6, 1916. Serial No. 737,658.

the circuit arrangement is in the .i or a Vlheatstonc bridge.

hm o shown, diagrammatically, a micropiano transmitter consisting of the stationary electrodes and 4 and a movable electrode 5. This transmitter is bridged across the line crmductors 6 and 7, one of these conductors being connected to each of the stationary electrodes respectively of the t ansmitter. The movable electrode 5 is munected to the grounded pole'of thebatcry B, while the opposite pole of the battery is connected to the two line conductors through the resistance coils 8 and 9. A series of receivers 10 are bridged across the line circuit, which receivers are conrluctively separated from the transmitter by means of the condensers 11 and 12.

In Fig. 2, I have shown the manner in which a series of these transmitters are combined. It is merely necessary to con meet the various pairs of line conductors in multiple to the same pole of the battery, and likewise the movable electrode of the various transmitters in multiple connection to the opposite poleof the battery. The line conductors are then connected to the bus bars 13 14, to which bus bars the amplifiers 15 are connected. The condensers 1i. and 12 are inserted in the conductors 6 and 7, between the bus bars 13 and 14 and the point Where the transmitters are connected to the conductors. The location of these condensers is quite important, as I find that much more ellicient results are 0bmined by placing these condensers in the conductors 6 and 7 before they are connected to the bus bars, than by placing these condensers between the bus bars and the amplifiers. These amplifiers can be of any desired construction, and they form no part of my invention, and I merely illustrate the same ciagranimatically, as the construction and operation of these amplifiers are Well understood in the art. These amplifiers then receive the current from the bus bars and repeat the same over the line conductors, across which are bridged the receivers 10. This circuit arrangement and the operation of the same can be more clearly understood by having reference to Fig. 3. It will be seen that the fixed resistances 8 and J form two sides of a Wheatstone bridge, while the variable resistances for the other two sides of the bridge consist of the two parts of the transmitter, the battery being connected at a point between the two parts of the transmitter.

It .is thought that the operation of the system will be clearly understood. The granular material of the transmitter while at rest furnishes a comparatively low resistance, but the resistance coils 8 and 9 are to prevent the of sufiiciently high resistance battery from becoming short circuited at this time. As soon as the transmitter is set in vibration, however, the resistance of the granular material rises very rapidly, and the resistance of the granular material then forms a large percentage of the total resistance. Accordingly, the variations in this resistance due to the operation of the transmitter cause a greater variation of poten-' tial at the points of the bridge to which the receivers are connected and, therefore, produce an amplified effect on those receivers. When a plurality of these circuits are combined, as in Fig. 2, the fluctuations of current in the line conductors, due to the variation in resistance of the granular material, are transmitted over these conductors through the condensers 11 and 12 to the bus bars 13 and 14, from which this current is taken off and passes through the amplifiers 15. The presence of the condensers 11 and 12 prevents any local circuits being set up through these bus bars to the other transmitters connected in multiple, and I find that by this circuit arrangement that the effects of the various transmissions are combined together in a very elficient manner, and there appears to be little or no tendency for variations set up by one transmitter to counteract or buck the variations set up by' another transmitter. I find that this system is particularly useful in the transmission of music where each one of the series 0 transmitters Will receive the vibrations from a particular instrument and then the combined effect is transmitted to the bus bars, to which I connect a number of amplifiers, and each one of the amplifiers then supplies ten or more receivers.

While I have shown one particular embodiment of my invention, it will be understood that I do not wish to be limited to the exact construction shown and described.

What I claim as my invention is:

1. In a telephone system, a plurality of pairs of line conductors, the conductors of each pair being connected together at one end, and connected in multiple to one pole of the battery, a transmitter bridged across each pair of said line eomluctors, each of said transmitters including three electrodes, the central electrodes of which are connected .in multiple to the opposite pole of the battery, and multiple connections betueen cor responding line conductors of each of said each of said pairs being pairs at a point beyond the connection of said transmitters to said line conductors.

2. In a telephone system, a plurality of pairs of line conductors, the conductors of each pair being connected together at one end and connected in multiple to one pole of the battery, a transmitter bridged across each pair of said line conductors, each of said transmitters including three electrodes the central electrodes of which are connected in multiple to the opposite pole of the battery, multiple connections between corresponding line conductors of each of said pairs at a point beyond the connection of said transmitters to said line conductors, and condensers inserted in said line conductors between said transmitter and said lastmentioned multiple connection.

3. In a telephone system, a

plurality of pairs of line conductors,

the conductors of each of said pairs being connected together at one end and multipled to one pole of a battery, a transmitter bridged across each of said pairs of line conductors, said transmitters comprising a pair of outer electrodes and a central electrode, one of said outer electrodes being connected to one of said line conductors, and the other outer electrode connected to the other line conductor, and said central electrode being connected to the opposite pole of the battery, and a pair of bus bars connected in multiple to the corresponding line conductors.

4. In a telephone system, a plurality of pairs of line conductors, the conductors of connected together at one end and multipled to one pole of a battery, a transmitter bridged across each of said pairs of line conductors, said transmitters comprising a pair of outer electrodes and a central electrode, one of said outer electrodes being connected to one of said line conductors, and the other outer electrode connected to the other line conductor, said central electrode being connected to the opposite pole of the battery, a pair of bus bars connected in multiple to the corresponding line conductors, and condensers inserted in said line conductors at a point between said bus bars and said transmitters.

5. In a telephone system, a pairs of line conductors, the conductors of each of said pairs being connected together at one end and multipled to one pole of a battery, a transmitter bridged across each of said pairs of line conductors, said transmitters comprising a pair of outer electrodes and a central electicde, one of said outer electrodes being connected to one of said line conductors, and the other outer electrode connected and said central electrode being connected to the opposite pole of the battery, a pair of bus bars connected in multiple to the corresponding line conductors, a plurality of plurality of to the other line conductor,

' amplifiers connected in multiple to said bus bars, and a plurality of receivers operatively connected with each of said amplifiers.

6. In a telephone system, a plurality of pairs of line conductors, the conductors of each of said pairs being connected together at one end and multiplcd to one pole of a battery, a transmitter bridged across each of said pairs of line conductors, said transmitters comprising a pair of outer electrodes and a central electrode, one of said outer electrodes being connected to one of said line conductors, and the other outer electrode connected to t other line conductor, and said central e ectrode being connected to the opposite pole of the battery, a pair of bus bars connected in multiple to the corresponding line conductors, condensers inserted in said line conductors at a point between said bus bars and said transmitters, a plurality of amplifiers connected in multiple to said bus bars, and a plurality of receivers operatively connected with each of said amplifiers.

, 7. In a telephone system, a pluralit, of circuits each comprising a pair of resistances forming two legs of a Wheatstone bridge, and a microphone transmitter having a pair of variable resistances, one in xed each of the other legs of said bridge, a battery having one pole connected in multiple between the pairs of fixed resistances, and the other pole connected in multiple to a point between said variable resistances and'v a plurality of receiving instruments connected in multiple to points between said fixed and variable resistances.

8. In a telephone system, a plurality of circuits each comprising a pair of fixed resistances forming two le s of a Wheatstone bridge, and a microp one transmitter having a pair of variable resistances one in each of the other legs of said bridge, a battery having one pole connected in multiple between the pairs of fixed resistances and the other pole connected in multiple to a point between said variable resistances and a plurality of receiving instruments connected in. multiple to points between said fixed and variable resistances and in series with condensers.

Signed by me at Chicago, Illinois, thi 16th day of December, 191

JOHN J. COMER.

Witnesses:

H. A. SWENARTON, E. H. Cmoe. 

